Match each magnetic quantity to what it describes.

• Magnetisation $\mathbf{M}$ → Magnetic moment per unit volume
• Auxiliary field $\mathbf{H}$ → A field whose curl counts free current only
• Curie temperature → Where a ferromagnet becomes paramagnetic
• Hysteresis loop area → Energy dissipated per magnetisation cycle

$\mathbf{M}$ measures the aligned moments, $\mathbf{H}$ keeps Ampère’s law usable, the Curie temperature is where ordering collapses, and the loop area is the energy paid per cycle.